Process of manufacturing low volatile coke



Dec. 12, 1933. G, MERKEL 1,939,457

' PROCESS OFMANUFACTURING Low voLATILE COKE Filed oct. 1s, 1928 2 sheets-sheet 1 6e@ rg Mer/ e/ INVENTOR A ATTORNEY Dec. 12, 1933. G. MERKr-:L

PROCESS OF MANUFACTURING LOW VOLATILE COKE Filed 001'.. 18, 1928 2 SheetS-Sheet 2 1 A 54M Mini@ 7am@ f d .j C

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Georg werke/ INVENTOR K ATTORNEY.

Patented Dec. 12, 1933 UNITEDv STATES PATENT oFFicE PRGCESS 0F MANUFACTURING LCW VOLATILE COKE Georg Merkel, Munich, Germany Application October 18, 1928, Serial No. 313,234, and in Germany October 31, 1927 2 Claims.

of good tar in the distillation of solid carbonizable material it has been proposed to distill the material at low temperatures, i. e. of maximum about 450 C. In such a process besides tar a kind of semi-coke is produced, which is unfit for numerous industrial purposes because of its high content of volatile matter and of its inferiorV solidity.

The object of the invention is to produce from any solid carbonizable material, such as coal, lignite, peat, wood and the like, a great quantity of a good tar and a low volatile coke, which can be used for metallurgical purposes.

Owing to the fact that the best tar is produced at temperatures not higher than about 450 C. and that for the production of va low volatile coke a temperature of at least about '750,c C. is necessary, it has already been tried to manufacture the coke by distillation in two steps, whereby the bulk of the tar is produced in the first step. However, the quality of the coke resulting from this process, particularly its hardness is not essentially different fromv coke obtained by the ordinary distillation.

It was found that the speed of temperature increase from the first to the secondV step of the distillation has considerable influence on the quality of the resulting coke. The faster and more sudden the heating is done after finishing the low temperature distillation, the harderl becomes the resulting coke. Probably this is caused by a sharp cracking of the bituminous matter remaining in the semi-coke on account of the fast heating whereby the constituents of the coke are somewhat cemented together.

According to the invention the new process of manufacturing a low volatile coke from solid carbonizable material consists in distilling the said material at a temperature up to about 450 C., and then subjecting it to an abrupt rise in temperature to at least about 750 C. at which temperature the coking is completed.

In my improved method the heating of the material takes place gradually to the temperature of about 450 C. Thereby the natural texture and solidity of the coal are saved as much as possible. A l

During the -following swift rise of temperature the cracking of the tar, of the remainder of bituminous matter, takes place, followed by complete coking. The fast rise of temperature not4 only results in a solidification of the coke,

but also in a shortening of the coking process, which means an increase of the efficiency of the retort or chamber. Preferably the coking temperature in the second step will rise to about 1000 C.

A sudden increase of temperature during the progressing distillation of the material in accordance with the'present invention is only practically possible if the heating of the distilling substanceat least in the second step-is done directly, i. e. by means of a hot circulating gas, e. g. producer gas. Therefore the material is coked with a stream of inert gas, that part of which first comes into contact with the raw material has in the highest case a temperature of about 450 C., which temperature abruptly changes to at least '750 C. in that part of the gas stream, which comes into contact with the material in the coking zone. Preferably the material passing through the retort or chamber 1 led in a counter current to the stream of inert gas.

Another feature of my invention is, that the e inert gas leaving the chamber or retort in counter current to the material with a low temperature has a temperature gradually rising along the stream of inert gas up to about 450 C., after which the temperature rises abruptly to '750--1000L1 C. at the gas streams entering the chamber or retort.

The dividing of the entire distilling process into two steps in a single .chamber or retort may be attained by introducing a stream of inert gas, which may be coal gas, producer gas, water gas or nitrogen at a temperature of about 750-1000 C. adjacent the coke outlet' of the chamber or retort and thereby coking said material, and injecting sufcient cold inert gas-of a temperature of between about 20 and 140 C. depending on the conditions of operation-into said gas stream after it has traversed the coking part of said chamber or retort to reduce its temperature to not higher than about 450 C. Therefore the material passing through the chamber or retort in a counter current is subject to an ordinary low temperature distillation in the rst step, and not before the second step coked fully by a sudden rise of temperature.

The intended temperature of the hot gas after it has been owing through the coking part of the chamber or retort can naturally be done also by mixing with injected steam having a temperature generally between 110 and 120 C., which is` to be applied in such quantities as to effect the intended drop in temperature. If no cheap steam (exhaust steam) is available, the injection of corresponding quantities of water in atomized form insures the desired result.

According to a modification the intended purpose of the process' is reached by exhausting the hot circulating gas, after it has traversed the coking zone, from the distilling material and withdrawing the gas into hollow walls defining the distilling zone to produce in said distilling zone by indirect heating thereof, a temperature of about 450 C. In this case the heating of the material is done indirectly in the first step, and only in the second step directly by the circulating hot gas.

The coke produced by this process has very good properties; it is solid, crisp, of good silver-gray color and very low hygroscopicity. Usually the proportion of fine-grained coke is insignificant.

For the application of the method, the chamber system is particularly suited. It permits an even flow of gas in the comparatively small single transverse section of each chamber, as well as an easy regulation and control' of the whole process, contrary to the large-chamber ovens which are frequently rendered inoperative. The subdivision into single chambers makes possible a large output, as the chambers, similar to the wellknown coke ovens, are built together in series. Appropriately in this case every two chambers may be coupled with one charging and discharging equipment.

An embodiment of my invention is illustratively exemplified in the accompanying drawings, in

which Figure 1 shows a horizontal sectional view of an oven taken on line 1--1 of Figure 2 and illustrates an oven heated exclusively by hot circulating gas; Figure 2 is a vertical sectional view taken on line 2-2 of Figure 1; and Figure 3 is a substantially vertical section of a modified con struction of Figures 1 and 2.

The oven is operated in the following manner: The lumps of raw material (e. g. lignite, coal, peat, wood) which retain about 6-10% moisture come from the openings 1 at the bottom of the reservoir 2, whichserves as a predrier and which is partly visible in the drawings, and slide over the roof-shaped heads of the chamber walls 3 into the chambers which contain, in the represented construction, an upper narrow part 4, and a lower wide portion 5 of the fuel bed. In the receding corner 6 within the chamber the nozzles 7, which serve to inject cold gas from the channel 8, open into the chambers. The hot gas used for distilling the fuel leaves the channel 9 through the bevel grate 10 into the chamber, runs through the material in the coking chamber 5, mixes with the cold gas near 6 and leaves the oven through the opening 11 after owing through the material in the low temperature part 4.

In order to succeed in equally distributing the gas throughout the entire transverse section of the chamber, it is necessary to provide that the gas will meet about the same resistance in each spot of the cross-section. This is accomplished by providing an equal length of path for every current of gas. In this .case this aim is reached by arranging the gas inlets 10a in such a way that the slope of the material resting in the oven adjusts itself about parallel to/,the bevel grate 10 which-forms the bottom of the chambers, so that the gas streams issuing from the several gas inlets pass vthrough substantially the same amount of material,

The finished low volatile coke is lcooled in a `suitable way and then discharged continually or intermittently. In the drawings a water jacket l2 is shown, the purpose of which is to cool the coke. A scraper 14 is moved forward and backward on the plate 13 to remove the coke from the cooling chamber.

A little different from this is the second form of construction, shown in Figure 3, which provides a system of mixed heating. The hot circulating gas flows through the bevel grate 15 and escapes, after running through the coking chamber 16, by the openings 17 into the heating channels 18 of the chamber walls 19, which form the lateral outline of the low temperature zone 20. In this oven the change from direct to indirect heating produces the desired sudden increase of the temperature of the material. In this' case the coal tar vapors are conveniently separated from the heating gas and exhausted by the opening 21.

It is advantageous to combine each pair of chambers to form a double-chamber with common discharging equipment as represented by Figure 2.

Besides it is advantageous to build the chambers in a series of two parallel rows, side by side, arranging the channels 22 which are supplying the gas between the two rows in order to obtaina better insulation.

The above described process as before stated is suited to the coking of all kinds of lump fuel, especially coal, lignite, peat, and wood. The process and the oven are extremely simple. The process, besides permits the production of ammonia from raw materials containing a high percentage of nitrogen, on account of the applied temperatures, as the yield of nitrogen is known to be favorably influenced by a temperature of about 850 C. The oven may be built exterior accessories. Through the low cost of lthe equipment of the oven the method operates economically even where the raw material is expensive.

I claim:

1. The process of manufacturing a low volatile coke from solid, carbonizable material, which comprises passing said material through a chamber or retort toward the coke outlet thereof, introducing a stream of inert gas at a temperature of about 750 to 1000 C. adjacent the coke outlet of the chamber or retort and thereby coking said material, and injecting sufficient cold inert gas into said gas stream after it has traversed the coking part of said chamber or retort to reduce its temperature to not higher thanabout 450 C.

2. The process of manufacturing Aa low` vola- GEORG MERKEL. 

